.app-index{
    
}
.app-index>ul:nth-of-type(1){
    padding-top:1rem;
    padding-bottom:0.5rem;
    display:flex;
    line-height:1.5rem;
    justify-content: space-around;
    background:red;
    position:fixed;
    top:4rem;
    left:0;
    right:0;
    font-size:1.2rem;
}
.app-index>ul:nth-of-type(1) .tab{
    color:white;
    border-bottom:3px solid white;
}
.app-index-tab{
    margin-top:7rem;
    width:100%;
    height:33rem;
    background:skyblue;
    font-size:3rem;
}